Nissan Qashqai Lost Power: How We Found a Defective Valve and Fixed It

The owner's Nissan Qashqai had suddenly lost power. It happened on a drive, not slowly over weeks. One moment it was fine, the next it was down on power, running rough and would not pull the way it should. The engine warning was on.

The car had already been to a workshop, where the spark plugs were changed in the hope of a quick fix. The problem stayed exactly the same. That is a useful clue. When fresh plugs do not change anything, the fault is usually deeper than ignition. The owner did not want to keep throwing small parts at it, so the ask was simple: find the real reason and fix it properly.

A plug change had already ruled out the easy answer. With the symptom pointing to one cylinder not firing properly, our team checked compression and found one cylinder down. A scan alone would not show why, so the only honest way to confirm it was to open the engine.

We removed the cylinder head and inspected the valves. One engine valve was defective. It was worn and no longer sealing, so that cylinder could not hold compression, which is exactly why the engine had lost power and run rough. We marked the faulty valve and showed the owner photos of the open head before quoting, so the reason for the repair was clear before any parts were ordered.

We also pointed out the parts around the head that were tired and worth doing while the engine was already open, so the owner could decide with the full picture in front of them.

Once the owner approved, we carried out a full engine top overhaul rather than patching one part.

• Removed and reconditioned the cylinder head, and replaced the defective valve so the cylinder seals and holds compression again.
• Replaced the timing chain set with its guides, so the renewed top end runs on a fresh timing drive.
• Replaced the VVT sensors, the water pump, and the fan belt with its tensioner.
• Renewed the valve cover gasket and plug seals, the timing cover o-rings, the main pulley with its oil seal, the intake manifold gasket and the fuel injector o-ring set, to stop oil and coolant leaks once everything was back together.
• Reassembled the engine, tested it, and road tested the car before handover.

We used OEM-grade engine parts. After the work, the engine started and drove with no problem.

This job came to about $8,000, which covered the head recondition and defective valve, the timing chain set with guides, VVT sensors, water pump, fan belt with tensioner, and the gaskets and seals renewed while the engine was open.

What moves the price is what the head reveals. A single worn valve with the rest of the top end in good shape sits at the lower end. If more valves, the timing drive or other worn parts need doing, the cost climbs. This is why we open and inspect first, then give a firm quote before any work begins.

This Nissan Qashqai (Engine top overhaul) was handled at 1 Car Service, an independent workshop in Sin Ming AutoCity, Singapore. We hold a 4.9★ rating from 1,775+ Google reviews.